Incidental congenitally corrected transposition of the great arteries (ccTGA) in an adult with suspected coronary artery disease: review on radiological features and pathophysiology

Abstract

We report a case of a 46-year-old woman who has presented to a peripheral hospital with progressive exertional dyspnoea and chest discomfort. The resting ECG showed features of left-sided ventricular hypertrophy. The initial chest radiograph was reported as cardiomegaly. Initial echocardiography revealed left atrial dilatation and 'left ventricular' hypertrophy with normal ejection fraction. She was treated as possible coronary artery disease and was subsequently referred to our centre for CT coronary angiography. Findings from the CT scan were consistent with congenitally corrected transposition of the great arteries (ccTGA). This report describes the radiological features of ccTGA, its associated cardiovascular anomalies, pathophysiology and potential complications.

Keywords: heart failure; radiology.

Figure 1

Frontal chest radiograph shows levocardia, cardiomegaly, slightly prominent pulmonary hilar vessels and opaque left costophrenic angle. Note the leftward location of the thoracic aorta at the left upper mediastinum (arrows).

Figure 2

Multiplanar reconstruction CT in four-chamber view of the heart in diastole (A) and systole (B) shows atrioventricular discordance. The mRV is hypertrophied and hypertrabeculated especially at mid to apical wall. The septal annulus of the tricuspid valve of mRV (black arrow) is apically displaced as compared with the posterior annulus of the mitral valve of mLV (curved arrow). Oblique sagittal views (C and D) demonstrate subaortic infundibulum (black arrowhead) separating the outflow aortic valve (red arrow) from the inflow tricuspid valve (yellow arrow), a characteristic feature of mRV. On the right side, the inflow mitral valve (white arrowhead) is in continuity with the outflow pulmonary valve (chevron arrow), a characteristic feature of mLV. AA, ascending aorta; LA, left atrium; mLV, morphologic left ventricle; MPA, main pulmonary artery; mRV, morphologic right ventricle; RA, right atrium.

Figure 3

CT image in axial view (A) shows the AA is immediately anterior to the MPA. The coronal oblique view (B) shows the ventriculoarterial discordance and the parallel course of the great arteries which is a characteristic feature of transposition of the great arteries (TGA). AA, ascending aorta; mLV, morphologic left ventricle; MPA, main pulmonary artery; mRV, morphologic right ventricle.

Figure 4

Axial multiplanar reconstruction CT at the level of the coronary sinus (A) shows the aortic root located to the left and slight anterior to the MPA. The LSCA originates from the anterior right coronary cusp and bifurcates into AD and Cx. The mRV artery arises separately from the anterior right coronary cusp and supplies the mRV free wall. The RSCA originates from the posterior coronary cusp and gives rise to PDA (not shown). Volume rendered images (B and C) further illustrate the coronary artery anatomy. AD, anterior descending artery; Cx, circumflex artery; LSCA, left-sided coronary artery; AO, aorta; MPA, main pulmonary artery; mRV, morphologic right ventricle; PDA, posterior descending artery; RSCA, right-sided coronary artery.